an alpha-D-glucosyl-(1->6)-alpha-D-glucosyl-(1->6)-alpha-D-glucosyl-(1->3)-1-alkyl-2-acylglycerol + 3'-phosphoadenylyl sulfate = a 6-sulfo-alpha-D-glucosyl-(1->6)-alpha-D-glucosyl-(1->6)-alpha-D-glucosyl-(1->3)-1-alkyl-2-acylglycerol + adenosine 3',5'-bisphosphate + H(+) — reaction